Typically, during semiconductor processing, a carefully controlled processing environment is established within a processing chamber. Temperature, pressure, gas content, and other aspects of the processing chamber are regulated and adjusted to optimize conditions for a given operation. Many substrate processing recipes necessitate an extremely low pressure environment within the processing chamber. This has traditionally been accomplished by externally mounting a turbine-type pump mechanism, known as a “turbo pump.”
In existing systems, chamber pressure may be manipulated by adjusting the rotational speed of the turbo pump. However, such configurations do not allow substantial flexibility in pressure profiles, since the only adjustable variable is the operating speed of the pump. Additionally, adjustment options are further limited because the location of the vacuum port is usually confined to a fixed location which penetrates the wall of the processing chamber.
Therefore, a processing chamber with improved vacuum pumping control features is needed.